It’s simple to use if you’re patient (6,8)
I believe the answer is:
herbal medicine
'you're patient' is the definition.
The definition suggests a singular noun which matches the answer.
'it's simple to use' is the wordplay.
I cannot quite see how this works, but
'simple' could be 'herb' (I've seen this before) and 'herb' is found in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
This explanation may well be incorrect...
'if' is the link.
Can you help me to learn more?
(Another definition for herbal medicine that I've seen is " Natural remedy".)